When you are going down on a girl, and right before she is about to orgasm, you stick your tongue in her A*hole (deep enough your lips touch), then jump up and french kiss her before she knows what's going on....
If timing is right, she should still have her eyes closed, and be unsuspecting!

I heard a girl scream from my roomate's bedroom... he told me he was gonna give his girlfriend a Hershy Kiss for Valentine's Day!